Sodium silicate based injection systems are used in a number of construction applications to create a stable foundation. For example, sodium silicate can be used to fill in the pores between the solid particle and the soil. This will displace as well as compact the soil in order to improve the load bearing characteristics of the soil.
Sodium silicate can also be used to mitigate settlement and collapse of dirt walls created during an excavation project. In many instances, sodium silicate grout can be injected underneath the foundation of a settling structure to prevent any further settlement.
Sodium silicate can only be utilized to seal a leak. For example, sodium silicate grout could be injected underneath a pump well casing that was leaking and/or beginning to sink. The injection of a proper amount of sodium silicate grout would stabilize the structure from additional sinking, seal any leak and fill the voids in the soil where water was seeping.
Sodium silicate and a catalyst are mixed together in water. The mixture will cure into a solid gel like substance after a period of time. This time period can vary based on factors such as heat and humidity. It is critical to have all of the mixture pumped into the ground before it cures to a solid and can no longer be pumped. If the mixture is sufficiently diluted with water, pumping will not be an issue; however the mixture will seep out of the void it was intended to fill and lose its effectiveness.
Conventional methods for preparing sodium silicate based grout is to batch mix all of the components. The ground injection pump will then suction from the batch mixing tank. When utilizing this method, any of the mixture that cures before being pumped becomes waste. This waste becomes extremely costly over time.
An example of an application of sodium silicate based grout injection is U.S. Pat. No. 6,897,186, which discloses an excavation fluid composition useful for enlarging a cavity in the earth includes a synthetic polymer and sodium silicate. The excavation fluid composition is formulated so as to enable the fluid in contact with unstable or sandy soils in the selected areas of the excavation to react and form silicate-based derivatives with lesser solubility, and movement and thus improve soil stability at the excavation wall. The grout in this application is batch mixed thereby creating waste of any grout that is not pumped before curing has occurred.
What is lacking in the art is a method for determining the proper proportion of soil stabilization material necessary for a particular soil and environmental conditions, and for the metering, inline mixing and pumping of a precise amount of materials necessary for optimum soil stabilization.